4 Solar Panels & High-Efficiency: The four solar panels can reach 20%-24% of conversion efficiency while providing enough power, which is 3-4 times faster than the ordinary solar charger. 25000mAh Huge Capacity: Built in Li-Polymer battery, solar portable charger is more than enough for your longtime travel, which can simultaneously charge 2 USB-powered devices for multiple times. Portable and Foldable: The 6.1 x 3.4 x 1.4 inches (when folded) compact size can easily squeeze in your backpack, offering portability and simplicity. It is also ideal for hanging on a backpack to solar charge while hiking or walking.